Terry was questioned soon after the slaying last month of Clay "C.J." Ether, sources close to the investigation said.

The motive for the stabbing remains unknown. Terry denied being in the boy's apartment building in the 5000 block of West Washington Boulevard, the sources said.

Authorities were led to Terry by DNA material recovered from the handle of the knife used to kill C.J., the sources said.

The handle had broken off from the blade and was found elsewhere in the building, the sources said. Tests showed both Terry's and C.J.'s DNA on the handle, the sources said. The knife reportedly belonged to the boy's family.

C.J. died Feb. 15 after he was stabbed in the chest in or near his family's apartment, police said.

Family members say he stumbled into his mother's bedroom in the middle of the night, blood pouring from his chest, and told his mother he had been stabbed.

C.J.'s mother, Kallie Ether, called 911, then called her sister about 1:30 a.m., said the sister, Vivian Shine.

When police arrived at the apartment that C.J. shared with his mother and 7-year-old sister, they found the boy with a knife wound in his chest, said Officer Kristina Schuler.

C.J. was taken to Loyola University Medical Center in Maywood, where he died of multiple stab wounds, said the Cook County medical examiner's office. His death was ruled a homicide, a spokesman said.

Family members said they did not know where C.J. was when he was stabbed or how he encountered his attacker, said Shine, his aunt.

"I don't know if the back door was unlocked, or what," she said. "I'm pretty sure [C.J.] was asleep. It was a school night."

The Illinois Department of Children and Family Services, which was informed of the stabbing as a matter of routine, had no prior contact with the Ether family, and it is not investigating C.J.'s death, said spokeswoman Kim Broome.

The 6th grader was a good student who liked sports and video games, according to family, friends and school officials.

Police still need to determine where C.J. was when he was stabbed, said Officer John Mirabelli.

C.J.'s brother, Cortez Boyd, 18, could not hold back tears as he talked about his brother at the time of the stabbing.

"I saw him ... about 8 p.m. when [C.J.] went to the store," Boyd said. That was the last time Boyd saw his younger brother, he said.

At the boy's school, Emmet Academy, Principal Jacqueline Robinson said pupils were shaken by C.J.'s death.

"There are children who are saying they're afraid about what happened," she said. "Some kids came to school upset and I've received calls already from parents. My staff is also upset and very concerned."

C.J. transferred in October to Emmet Academy, 5500 W. Madison St., from nearby Spencer Elementary School, Robinson said. Robinson said he was a good student and teachers were fond of him.

Residents at the Ether family's apartment building said Wednesday that a patio area and an alley directly behind the family's apartment was known for heavy drug activity.

"People hang out in the alley all day and night, smoking crack," building resident Robert Jones said.

But police said it is too early to comment on whether that had anything to do with C.J.'s stabbing.

Neighbors were baffled over how an 11-year-old could end up with stab wounds inside his own building in the middle of the night.

"It's scary," said Tina Grady, a neighbor. "You never know exactly what went on. If someone tried to break in, or he came to answer the door. It doesn't add up."